CVE-2026-77255

Name of the Vulnerable Software and Affected Versions MCP Atlassian versions prior to 0.22.0

Description A confused deputy issue exists where the server can be forced to read arbitrary local files and attach them to a Jira issue, leading to the exfiltration of sensitive host files and environment secrets. The problem occurs in the update issue tool handler, where the attachments parameter is converted into local paths and routed to the upload implementation without workspace validation. The implementation fails to restrict paths to a safe workspace, prevent directory traversal using ../ sequences, or validate ownership. This allows a restricted agent to use the privileged MCP process to access system-level files, such as /proc/self/environ, and upload them to a Jira ticket.

Recommendations Update MCP Atlassian to version 0.22.0. As a temporary workaround, avoid using the attachments parameter in the update issue tool.